Method for the production of 2-bromo-5,6,7,8-tetrahydroquinoline and the analogous 2-bromo-trimethylene and pentamethylene pyridines

ABSTRACT

The invention concerns compounds of formula I ##STR1## or a salt thereof, wherein R 1  and R 2  each independently represent hydrogen, lower alkyl, lower alkoxy, carboxyloweralkyl, carboxy, hydroxyloweralkyl, halogen, haloloweralkyl, lower alkoxycarbonyl, optionally substituted aryl or optionally substituted aralkyl, n represents an integer from 3 to 6; R 3  which is optionally present represents single or multiple substitution on one or more of the aliphatic carbons by one or more substituents selected from lower alkyl, optionally substituted aryl and optionally substituted aralkyl; A represents a group of formula (i) or (ii) below: 
     
         --CR.sup.4 R.sup.5 --(CR.sup.6 R.sup.7).sub.m --           (i) 
    
     
         --CX--(CR.sup.6 R.sup.7).sub.m --                          (ii) 
    
     in which R 4 , R 6  and R 7  each independently represent hydrogen or lower alkyl (providing that when R 5  is NH 2 , R 4  is hydrogen); m is 0 or 1; R 5  represents hydrogen, NH 2 , OH or loweralkoxy, and X is ═O, ═NH or ═NOH, the attachment of A to B being from either end, and B represents an optionally substituted aryl or heteroaryl radical which compounds possess anti-inflammatory activity. Also disclosed is a process for preparing a useful intermediate to compounds of formula I.

This is a division of application Ser. No. 07/367,531 filed June 16,1989 now U.S. Pat. No. 4,975,431.

This invention relates to heterocyclic compounds, more particularly topyridine derivatives, processes for preparing them, pharmaceuticalcompositions containing them and to intermediates therefor.

This invention provides compounds of formula ##STR2## or a salt thereof,wherein R¹ and R² each independently represent hydrogen, alkyl, alkoxy,carboxyalkyl, carboxy, hydroxyalkyl, halogen, haloalkyl, alkoxycarbonyl,optionally substituted aryl or optionally substituted aralkyl, nrepresents an integer from 3 to 6; R³ which is optionally presentrepresents single or multiple substitution on one or more of thealiphatic carbons, eg. by one or more substituents selected from loweralkyl, optionally substituted aryl and optionally substituted aralkyl; Arepresents a group of formula (i) or (ii) below:

    --CR.sup.4 R.sup.5 --(CR.sup.6 R.sup.7).sub.m --           (i)

    --CX--(CR.sup.6 R.sup.7).sub.m --                          (ii)

in which R⁴, R⁶ and R⁷ each independently represent hydrogen or loweralkyl (providing that when R⁵ is NH₂ R⁴ is hydrogen); m is 0 or 1; R⁵represents hydrogen, NH₂, OH or loweralkoxy, and X is ═O, ═NH or ═NOH,the attachment of A to B being from either end; and B represents anoptionally substituted aryl or heteroaryl radical.

By the term aryl as used herein is meant any monovalent carbocyclicradical possessing aromatic character and includes groups having 6 to 10carbon atoms such as phenyl and naphthyl. By the term heteroaryl as usedherein is meant any monovalent heterocyclic group possessing aromaticcharacter and includes groups having 5 to 10 ring atoms and one or moreheteroatoms selected from oxygen, nitrogen and sulphur. Examples ofheteroaryl radicals are furyl, thienyl, pyrrolyl, pyridinyl,pyrimidinyl, quinolyl, isoquinolyl, benzimidazolyl, thiazolyl andimidazolyl.

The term alkyl when used to signify a group or part of a group such ashydroxyalkyl or aralkyl means any straight or branched saturatedaliphatic hydrocarbon especially those having 1 to 6 carbon atoms, eg.1-4 carbon atoms. Examples are methyl, ethyl, n-propyl, isopropyl,n-butyl, n-pentyl and n-hexyl.

By the term `optionally` substituted is meant optional substitution oncarbon atoms by one or more substituents, eg. substituents commonly usedin pharmaceutical chemistry, eg. halogen (eg. Cl,Br,F), alkyl, alkyloxy,haloalkyl (eg. CF₃), or haloalkoxy (eg. CHF₂ O--, CF₃ CH₂ O--), NO₂,NH₂, CN, alkylamino, dialkylamino, carboxy, alkyloxycarbonyl, acyl,acylamino, aryl, (eg. phenyl) or aminoalkyl.

The term `lower` as used herein to qualify a group means such a groupcontains 1 to 6 carbon atoms.

Examples of the groups R¹ and R² are independently hydrogen, lower alkyl(eg. methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl and n-hexyl),--COOH, --COOlower alkyl (eg. COOMe, COOEt), --CH₂ OH, Br, Cl, CF₃, OMe,optionally substituted phenyl or optionally substituted benzyl.

Preferred values of n are 3,4, or 5 such that the compounds have one ofthe following formulae ##STR3## Compounds of formula Ic are mostpreferred.

Examples of R³ are one or more substituents selected from methyl, ethyl,methoxy, ethoxy, phenyl, phenyl substituted by halogen, lower alkyl orlower alkoxy, benzyl and benzyl substituted by halogen, lower alkyl orlower alkoxy. Examples of multisubstitution on one carbon atom isgem-dimethyl.

Examples of R⁴, R⁶ and R⁷ are independently hydrogen, methyl and ethyl.

The linkage of --A-- to the pyridine ring and B can be either way roundso that examples of --A--B are --CHOH--B, --CHOHCH₂ --B, --CH₂ CHOH--B,--CO--B, --COCH₂ B, --CH₂ COB, --CH(OCH₃)--B, --CH(OCH₃)CH₂ B and --CH₂CH(OCH₃)--B. Preferably A is --CHOH-- or --CO--.

Examples of B are phenyl, pyridyl (eg. pyrid-2-yl), 1-naphthyl,2-naphthyl which groups may be substituted as defined herein, forexample by one or more substituents selected from lower alkyl, loweralkoxy, halogen, haloloweralkyl, nitro, amino, lower alkylamino, cyano,carboxy, lower alkoxycarbonyl and lower alkylcarbonyl.

In a preferred aspect this invention provides compounds of formula##STR4## or salts thereof, wherein n represents 4 or 5; R⁸ representslower alkyl, halogen, carboxy, loweralkoxy; R⁹ represents hydrogen or alower alkyl group; A¹ represents --CO-- or --CHOH-- and B¹ representsoptionally substituted phenyl, especially where the substituent isselected from one or more of the following: lower alkyl, (eg. o-,m-orp-methyl); halogen (eg. o-,m-or p-chloro or bromo); lower alkoxy (eg.o-,m- or p-methoxy), and carboxy, eg. o-,m- or p-carboxy. Other examplesof B¹ (and B) include 2,4-dimethylphenyl; 3,4-dimethylphenyl4-ethylphenyl; 4-isopropylphenyl, 4-isobutylphenyl.2-methoxy-4-methylphenyl, 2-chloro-4-methylphenyl.

The compounds of formula I can possess one or more asymmetric centresand hence optical isomers and mixtures thereof are possible, eg. when Ais CHOH or R³ represents monosubstitution. All such isomers and mixturesthereof are included within the scope of this invention. Where anyreaction process produces mixtures of such isomers standard resolutiontechniques may be applied to separate a specific isomer.

The compounds of formula I may be obtained in free base form or as acidaddition salts as desired. Examples of such salts include salts withpharmaceutically acceptable acids such as hydrochloric, hydrobromic,hydroiodic, sulphuric, phosphoric, nitric, acetic, citric, tartaric,fumaric, succinic, malonic, formic, maleic acid or organosulphonic acidssuch as methane sulphonic or p-toluene sulphonic acids.

When acidic substituents are present it is also possible to form saltswith bases eg. alkali metals (such as sodium) or ammonium salts. Suchsalts of the compounds of formula I are included within the scope ofthis invention.

When basic substituents are present then quaternary ammonium salts maybe formed by quaternizing with an alkylating agent such as alkyl, oralkyl halides.

The compounds of formula I possess pharmaceutical activity in standardtests, in particular anti-inflammatory activity. Anti-inflammatorycompounds of the non-steroidal type currently available generally have atendency to cause gastric irritation and some are markedly ulcerogenic.It has surprisingly been found that in standard tests compounds offormula I appear to be devoid of ulcerogenic properties even at highdoses.

The compounds of formula I were tested for anti-inflammatory activity inthe following test procedures:

PROCEDURE 1

Anti-inflammatory activity of a compound is assessed by its ability toinhibit experimentally induced edema in the hind paw of the rat.

Groups of six male Sprague-Dawley rats (Charles River), weighing between150-165 g, were used in these experiments. Drugs were administered p.o.in 0.5% methylcellulose (400 centipoise). One hour after administeringdrugs or vehicle, 0.1 ml of 1% carrageenan was injected subplantar intothe right hind paw. Right hind paw volumes (ml) were measured prior tocarrageenan injection using a mercury plethysmograph (ie. zero timereading). After three hours, the right hind paw volumes were re-measuredand paw edema was calculated for each rat by subtracting the zero timereading from the three hour reading. The percent change in paw edema wascalculated according to the formula: ##EQU1## The Dunnett's test wasused to determine statistical significance (P<0.05).

In the above test representative compounds of formula I gave the resultsshown in TABLE I.

                  TABLE 1                                                         ______________________________________                                        Compounds of Mean Paw    Number   Average %                                   formula I    Edema @ 3   of       change @                                    Dose 50 mgs/kg                                                                             hours ml + S.E                                                                            Assays   +3 hours                                    ______________________________________                                        Control       1.1 ± 0.05                                                                            100      --                                          1-(6,7,8,9-Tetra                                                                           0.45 ± 0.06                                                                            2        -59                                         hydro-3-methyl-5H-                                                            cyclohepta[b]-                                                                pyrid-2-yl)-1-                                                                (4-methylphenyl)                                                              methanol(Example 1)                                                           6,7,8,9,-Tetrahydro-                                                                       0.47 ± 0.05                                                                            2        -58                                         3-methyl-2-(methyl-                                                           benzoyl)-5H-cyclo-                                                            hepta[b]pyridine,                                                             hydrochloride                                                                 (Example 2)                                                                   1-(6,7,8,9-Tetra-                                                                          0.83 ± 0.06                                                                            2        -24                                         hydro-5H-cyclohepta                                                           [b]pyrid-2-yl)-                                                               1-(4-methylphenyl)                                                            methanol (Example 3)                                                          1-(6,7,8,9-Tetrahydro-                                                                     0.51 ± 0.08                                                                            2        -54                                         3-methyl-                                                                     5H-cyclohepta-                                                                [b]pyrid-2-                                                                   yl)1-phenylmethanol                                                           ______________________________________                                    

Compounds which inhibit the swelling by about 20% are considered ofinterest. The results show that all the compounds were active with thecompounds of Examples 1,3 and 4 demonstrating marked anti-inflammatoryactivity at the dose level tested.

PROCEDURE 2

In this procedure polyarthritis is induced in male Lewis strain rats bythe injection of a tubercle bacilli in the subplanter tissue of theright hind paw.

Groups of ten male Lewis rats (Charles River), weighing between 150-170g, were injected s.c. into the right hind paw with dessicatedMycobacterium butyricum (0.5 mg/0.1 ml) suspended in light mineral oil.Drugs were administered orally in 0.5% methylcellulose from day 0 to 15(except weekends). Both hind paw volumes (ml) were measured by mercuryplethysmography at the time of injection of adjuvant (day 0). Pawvolumes were measured on day 4 (injected paw only) and on day 16(uninjected paw) to determine the nonspecific andimmunologically-induced inflammation, respectively. Drug effects wereexpressed as a percentage change from vehicle-treated arthriticcontrols.

Active compounds will either prevent or reverse the joint swelling andassociated sequella of polyarthritis. A % change of about 20% fromcontrol is regarded as noteworthy.

In this test in a series of experiments compounds of formula I gave theresults shown in Table 2.

                  TABLE 2                                                         ______________________________________                                                                     % Change                                                                      from                                             Compound of formula I                                                                            Dose level                                                                              Control                                          ______________________________________                                        1-(6,7,8,9-tetrahydro-3-                                                                         30 mg/kg  -47%                                             methyl-5H-cyclohepta[b]-                                                      pyrid-2-yl)-1-(4-methyl-                                                      phenyl)methanol                                                               6,7,8,9-tetrahydro-3-                                                                            30 mg/kg  -26%                                             methyl-2-(4-methylbenzoyl)-                                                   5H-cyclohepta[b]pyridine,                                                     hydrochloride                                                                 1-(6,7,8,9-tetrahydro-5H-                                                                        30 mg/kg  -33%                                             cyclohepta[b]-pyrid-2-                                                        yl)1-(4-methylphenyl)                                                         methanol                                                                      1-(6,7,8,9-        30 mg/kg  -45%                                             tetrahydro-3-methyl-                                                          5H-cyclohepta[b]-                                                             pyrid-2-yl)-1-phenyl-                                                         methanol                                                                      ______________________________________                                    

The results in Table 2 show the above-mentioned compounds of formula Iexhibit marked antiflammatory activity in the test.

In standard tests investigating gastric irritation representativecompounds of formula I, namely1-(6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methanol and6,7,8,9-tetrahydro-3-methyl-2-(4-methylbenzoyl)-5H-cyclohepta[b]pyridine,hydrochloride did not show any effect at the highest dose level testedof 300 mg/kg.

The compounds of formula I may be prepared by various methods all ofwhich are included in the scope of this invention.

A first method for preparing compounds of formula I wherein A is --CR⁴R⁵ --(CR⁶ R⁷)_(m) -- where R⁵ is OH and R⁴, R⁶, R⁷ and m are as definedabove comprises reacting a compound of formula ##STR5## wherein R¹, R²,R³ and n are as defined above, p is 0 or 1 and M is sodium, potassium,lithium, Mghal where hal is halogen, eg. chlorine, bromine or iodineproviding that hal is not chlorine when p is 0, with a compound offormula ##STR6## wherein B, R³, R⁶ and R⁷ are as defined above and q is0 or 1 providing that p+q is 0 or 1, followed by protonation.

The reaction is conveniently carried out under anhydrous conditions inan appropriate inert solvent eg. tetrahydrofuran, toluene, diethylether, an alkane (such as hexane) or a cycloalkane (eg. cyclohexane) ormixtures of such solvents at or below room temperature. Preferably thestarting material of formula II is prepared in situ and the same solventused for reaction with the compound of formula III. The final step inthe reaction is to protonate the intermediate complex, eg using wateralcohol or an acid. In the aforementioned reaction any carbon atom epito the nitrogen (for example the 9-position when n is 5) may beprotected prior to reaction for example by using one or two organicsilyl protecting groups, eg. trialkylsilyl such as trimethylsilyl andremoving the protecting group(s) after the reaction.

The starting material of formula II may generally be prepared bymetallation reactions from appropriate corresponding compounds offormula ##STR7## optionally protected in the epi position where Z ishydrogen or halogen and n,p,R¹,R², R³ and R⁶ and R⁷ are as definedabove. For example the starting material of formula II wherein M islithium, sodium or potassium may be prepared by reacting a compound offormula IV wherein Z is hydrogen or bromine or iodine with a metalalkyl, eg. MR¹⁰ wherein M is Li, Na or K and R¹⁰ is alkyl, aryl oraralkyl, for example n-butylithium. Compounds of formula II where M isMghal may be prepared by treating a compound of formula IV wherein Z ishalogen with magnesium under conditions known for the preparation ofGrignard reagents.

Compounds of formula IV are known compounds or can be made by knownmethods for analogous compounds. For example5,6,7,8-tetrahydroquinolines can be prepared by reacting3-aminoacroleins with cyclohexanones according to the method ofBreitmaier and Bayer (Tet Letts 1970, 38, 3291). Similarly6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridines and cyclopenta[b]pyridinescan be prepared by reacting respective cycloheptanone or cyclopentanoneswith 3-aminoacroleins (eg. 3-amino-2-methylacrolein). These and othermethods are described in UK Patent Specification 1,432,378.

Another aspect of this invention provides a new and particularlyconvenient route to compounds of formula IV wherein p is O and Zrepresents bromine. Such compounds may be prepared by reacting acompound of formula ##STR8## wherein n,R¹,R² and R³ are as defined abovewith either bromine or HBr and bromine in an inert solvent, such as analkanoic acid eg. acetic acid or halocarbon, eg. methylene dichloride.This is believed to be the first direct cyclisation route to2-bromo-cycloalkenopyridines. Previously such compounds were prepared byhalogenating a corresponding 2-hydroxypyridine. The new process providesa particularly useful route via the appropriate intermediates ultimatelyto compounds of formula I wherein n=5. The reaction may be carried outwithout heating if desired using approximately equimolar quantities ofbromine and compound of formula VII. When HBr is used the amount mayvary from a catalytic amount to a molar excess, eg. 5M.

A further aspect of this invention provides intermediates of formulae IIand IV wherein n is 5.

Compounds of formula I wherein A is --CX--(CR⁶ R⁷)_(m) -- where X is ═NHand m, R⁶ and R⁷ are as defined above may be prepared by reacting acompound of formula: ##STR9## (if required protected in the epiposition) wherein n, R¹,R² and R³ are as defined above, p is 0 or 1 andM¹ is lithium, sodium, potassium or Mghal where hal is chlorine, bromineor iodine, with a nitrile of formula:

    B(CR.sup.6 R.sup.7).sub.q CN                               (VI)

wherein B, R⁶ and R⁷ are as defined above and q is 0 or 1 providing thatp+q=0 or 1 and if required removing any protecting group. The abovereaction may be conveniently carried out at or below room temperature inan inert solvent under anhydrous conditions.

Compounds of formula I wherein A is --CR⁴ R⁵ --(CR⁶ R⁷)_(m) -- whereinR⁵ is amino, R⁴ is hydrogen and m,R⁶ and R⁷ are as defined above, may beprepared by a process which comprises reducing a corresponding compoundof formula I wherein A is --CX--(CR⁶ R⁷)_(m) -- where X is ═NH. Thereduction is conveniently carried out using an alkali metal borohydride,such as sodium borohydride in alcohol solvent, eg. ethanol.

Compounds of formula I wherein A is --CO--(CR⁶ R⁷)_(m) -- where m,R⁶ andR⁷ are as defined above may be prepared by a process which comprises

a) hydrolysing a compound of formula I wherein A is --CX--(CR⁶ R⁷)_(m)-- where X is═NH or═NOH, or

(b) oxidising a compound of formula I wherein A is --CR⁴ R⁵ --(CR⁶R⁷)_(m) -- wherein R⁴ is hydrogen, R⁵ is OH and m, R⁶ and R⁷ are ashereinbefore defined. The hydrolysis step (a) may be carried out usingan aqueous acid with heating. The oxidation step (b) may be carried outusing an oxidation agent known for oxidising alcohols to ketones, eg.manganese dioxide.

Where the product of a reaction is a ketone then the oxime derivativethereof may de prepared in the usual manner eg. using hydroxylamine.Such derivatives may be converted to the ketone by hydrolysis.

When a compound of formula I is prepared in which R⁵ is OH then thatcompound may be converted to a compound of formula I wherein R⁵ is --O--lower alkyl by processes known for lower alkyl etherification (eg.Williamson Synthesis, Merck Index 10th Edition page ONR-96 andreferences cited therein). For example the lower alkyl ether may beprepared by first forming the alkali metal salt of the alcohol using analkali metal hydride, then reacting with an alkyl halide, eg. methyliodide.

Compounds of formula I wherein R⁵ is hydrogen can be prepared by methodsdisclosed in UK Patent Specification 1,432,378 or by analogous methods.They may also be prepared by reducing corresponding alcohols usinghydrogenation techniques. For example compounds of formula I wherein R⁵is OH may be reduced by hydrogenation using palladium charcoal to givethe corresponding compound of formula I wherein R⁵ is hydrogen.

Compounds of formula II which are useful as intermediates are novelcompounds within the scope of this invention. Included within theseintermediates are those having formula II in which the carbon epi to thenitrogen is protected by one or two organic silyl protecting groups eg.by trialkylsilyl. Accordingly the intermediates can be represented byformula IIa ##STR10## wherein n,p,R¹,R²,R³,R⁶ and R⁷ are as hereinbeforedefined, M is Na, K, Li or MgHal where Hal is a halogen, and P¹ and P²each represent optional organic silyl protecting group on the carbon epito the nitrogen.

Starting materials for the processes described herein are knowncompounds or can be prepared by analogous methods for known compounds.

This invention also provides pharmaceutical compositions comprising acompound of formula I or a pharmaceutically acceptable salt thereof.

For the pharmaceutical compositions any suitable carrier known in theart can be used. In such a composition, the carrier may be a solid,liquid or mixture of a solid and a liquid. Solid form compositionsinclude powders, tablets and capsules. A solid carrier can be one ormore substances which may also act as flavouring agents, lubricants,solubilisers, suspending agents, binders, or tablet disintegratingagents; it can also be encapsulating material. In powders the carrier isa finely divided solid which is in admixture with the finely dividedactive ingredient. In tablets the active ingredient is mixed with acarrier having the necessary binding properties in suitable proportionsand compacted in the shape and size desired. The powders and tabletspreferably contain from 5 to 99, preferably 10-80% of the activeingredient. Suitable solid carriers are magnesium stearate, talc, sugar,lactose, pectin, dextrin, starch, gelatin, tragacanth, methyl cellulose,sodium carboxymethyl cellulose, a low melting wax and cocoa butter. Theterm "composition" is intended to include the formulation of an activeingredient with encapsulating material as carrier, to give a capsule inwhich the active ingredient (with or without other carrier) issurrounded by carriers, which is thus in association with it. Similarlycachets are included. Sterile liquid form compositions include sterilesolutions, suspensions, emulsions, syrups, and elixirs. The activeingredient can be dissolved or suspended in a pharmaceuticallyacceptable carrier, such a sterile water, sterile organic solvent or amixture of both. The active ingredients can be often be dissolved in asuitable organic solvent, for instance aqueous propylene glycolcontaining from 10 to 75% of the glycol by weight is generally suitable.Other compositions can be made by dispersing the finely-divided activeingredient in aqueous starch or sodium carboxymethyl cellulose solution,or in a suitable oil, for instance arachis oil. Preferably thepharmaceutical composition is in unit dosage form, the composition issub-divided in unit doses containing appropriate quantities of theactive ingredient; the unit dosage form can be a packaged composition,the package containing specific quantities of compositions, for examplepacketed powders or vials or ampoules. The unit dosage form can be acapsule, cachet or tablet itself, or it can be the appropriate number ofany of these in packaged form. The quantity of active ingredient in aunit dose of composition may be varied or adjusted from 10 to 500 mg ormore, eg. 25 mg to 250 mg, according to the particular need and theactivity of the active ingredient. The invention also includes thecompounds in the absence of carrier where the compounds are in unitdosage form. Based on the results from animal studies the dosage rangefor the treatment of humans using a compound of formula I will be in therange from about 5 mg to 2 g per day depending on the activity of thecompound.

The following Examples illustrate the invention and methods forpreparing compounds of the invention.

EXAMPLE 11-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methanol

a) A 1.36M solution of n-butyl lithium in hexane(19 ml) in THF (20 ml)was treated with a solution of6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyridine (4.0 g, 0.025 m) intetrahydrofuran (THF) (5 ml) at 0° C. After 0.5 hours the solution wasblown over, under nitrogen pressure, into a solution of trimethylsilylchloride (10 ml) in THF (30 ml) cooled to 0° C. After 0.5 hours thesolvent was removed under reduced pressure and the residue treated withhexane, filtered and evaporated to give an oil containing6,7,8,9-tetrahydro-3-methyl-9-trimethylsilyl-5H-cyclohepta[b]pyridine.

b) The oil from step (a) was dissolved in THF (50 ml) and a 1.36Msolution of n-butyl lithium in hexane (19 ml) was added at 0° C. Themixture was stirred at this temperature for a further 0.5 hours.4-Methylbenzaldehyde (3.6 g, 0.03 m) in THF (5 ml) was added rapidly at0° C. and the mixture stirred for a further 0.25 hours. A solution of 2Mhydrochloric acid (60 ml) was added and stirred for 0.25 hours, thenseparated. The aqueous phase was separated and basified with solidpotassium carbonate and then extracted with chloroform. The combinedchloroform extracts were washed with water, dried (MgSO₄) andevaporated. The residue was treated with ether and the crystallisedmaterial collected and dried to give the title compound (2.2 g) m.p.143°-5° C.

Analysis: Found C, 81.4; H, 8.3; N, 4.7. C₁₉ H₂₃ NO requires C, 81.1; H.8.2; N, 5.0%.

EXAMPLE 2 6,7,8,9-Tetrahydro-3-methyl-2-(4-methylbenzoyl)-5H-cyclohepta[b]pyridine

1-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methanol(2.0 g) (prepared according to Example 1) in toluene (50 ml) withmanganese dioxide (6.1 g) was refluxed and water collected in a Dean andStark apparatus. The cooled solution was filtered and the solventevaporated under reduced pressure to give a gum. This was dissolved indiethyl ether and treated with ethereal HCl. A solid precipitated andwas collected by filtration and dried to give the title compound as thehydrochloride (1.8 g 80%) m.p. 172°-4° C.

Analysis: Found C, 72.1; H. 7.1; N, 4.8 C₁₉ H₂₁ NO HCl requires C,72.25;H, 7.0; N, 4.4%.

EXAMPLE 31-(6,7,8,9-Tetrahydro-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methano

6,7,8,9-Tetrahydro-5H-cyclohepta[b]pyridine (7.4 g 0.05 m) intetrahydrofuran (100 ml) was cooled to -10° C. and treated with a 1.57Msolution of n-butyl lithium in n-hexane (32 ml), then stirred at -10° C.for a further 0.5 hours. 4-Tolualdehyde (10 g 0.083 m) intetrahydrofuran (10 ml) was added rapidly and the mixture allowed towarm to room temperature, then water and diethyl ether were added. Thecombined ether extracts were treated with 2N hydrochloric acid and theaqueous acid extract which separated was basified with solid sodiumcarbonate and then extracted with chloroform. The combined chloroformsolutions were washed with water, dried (MgSO₄) and evaporated to givean oil. This was purified by chromatography using silica columns elutedwith diisopropyl ether or chloroform. The purification was monitored bytlc using diisopropyl ether and chloroform on silica plates or sampleswere silylated with 1-(trimethylsilyl)imidazole and injected on a g.l.c.(injection temp 200° C.) with a 25 meter BPI column, running atemperature programme from 120° to 300° C. at 10° C./min, thenisothermal and carrier gas helium at 10 psi. The title compound having aretention time 17.32 minutes was isolated and converted into thehydrochloride salt by dissolving in diethyl ether and treating withethereal HCl (1.5 g mp 168°-170° C.).

Analysis: Found C, 70.0; H, 7.4; N, 4.55 C₁₈ H₂₁ NO. HCl, 0.25 H₂ Orequires C, 70.1; H, 7.4; N, 4.5%.

EXAMPLE 41-(6,7,8,9-Tetrahydro-5H-cyclohepta[b]pyrid-2-yl)-1-phenylmethanol

6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyridine (4.42 g, 0.025 m)in tetrahydrofuran (50 ml) was cooled to -40° C. under nitrogen andtreated with n-butyl lithium in n-hexane (1.57 molar soln, 16 ml) andallowed to warm to 0° C. The solution was cooled to -70° C. and treatedwith a solution of benzaldehyde (4 ml) in tetrahydrofuran (10 ml) andallowed to warm to room temperature, then water and diethyl ether wereadded. The organic phase was separated and extracted with 2Nhydrochloric acid. The acid phase was made basic with solid sodiumcarbonate and then extracted with chloroform. The combined chloroformextract was washed with water, dried (MgSO₄) and evaporated underreduced pressure to give a gum. This was dissolved in n-hexane and thecrystallised material collected by filtration. This was purified bychromatograpy on silica using diisopropyl ether: chloroform (9:1 byvolume) as eluent. The isolated solid was triturated in diisopropylether give 1-(6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-phenylmethanol (1.1 g) m.p. 130°-2° C.

Analysis: Found C, 80.95; H, 8.2; N, 5.2 C₁₈ H₂₁ NO requires C, 80.9; H,7.9; N, 5.2%.

EXAMPLE 56,7,8,9-Tetrahydro-3-methyl-2-(1-methyloxy-4-methyl-benzyl)-5H-cyclohepta[b]pyridine

1-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methanol(2.0 g 0.007 m) was added to sodium hydride (0.35 g, 50% dispersion inoil, 0.007M, washed with 40-60 petrol) suspended in dimethylformamide(20ml). After evolution of hydrogen had ceased, methyl iodide (0.5 ml) wasadded and the mixture stirred at room temperature for 0.5 hours. Waterwas added and the mixture extracted with diethyl ether. The combinedether extracts were treated with 2N hydrochloric acid. The aqueous acidsolution was separated, basified with solid sodium carbonate andextracted with chloroform. The combined chloroform extracts were washedwith water, dried (MgSO₄) and evaporated. The residue was purified bychromatography on silica and eluted with chloroform to give the titlecompound as a gum. This was dissolved in diethyl ether and treated withethereal HCl to give the crystalline hydrochloride salt, 1.4 g m.p.144°-6° C.

Analysis: Found C, 72.1; H, 7.9; N, 4.4 C₂₀ H₂₅ NO. HCl requires C,72.4; H, 7.9; N, 4.2%.

EXAMPLE 61-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-methyl-1-(4-methylphenyl)methanol

To a 1.56M solution of n-butyl lithium in n-hexane (13 ml) in toluene(20 ml) at -20° C. under nitrogen, was added a solution of2-bromo-3-methyl-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine (4.8 g 0.02m) in toluene (20 ml) and kept at -20° C. for 0.5 hours. A solution of4'-methylacetophenone (3.0 g 0.022 m) was added and the mixture allowedto warm to room temperature and water added. The organic phase wasseparated and extracted with 2 N hydrochloric acid. This was basifiedwith solid sodium carbonate, then extracted with chloroform. Thecombined chloroform extracts were dried (MgSO₄) and evaporated underreduced pressure. The residue was purified by chromatography on silicausing chloroform as eluent to give a gum. This was dissolved in etherand treated with ethereal HCl to give the title compound as thehydrochloride, three quarter hydrate salt (1.95 g) m.p. 162°-4° C.

Analysis: Found C, 69.2; H, 8.0; N, 4.1 C₂₀ H₂₅ NO HCl. 0.75H₂ Orequires C, 69.55; H, 7.7,N, 4.1%.

EXAMPLE 76,7,8,9-Tetrahydro-3-methyl-2-(4-methylphenyl)-5H-cyclohepta[b]pyridine

1-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methanol(3.0 g) was dissolved in ethanol (150 ml) and added to 10% Pd/C (1 g)under nitrogen. 2M Sulphuric acid (5 ml) was added and the mixturehydrogenated at 50 psi until hydrogen uptake had ceased. The catalystwas removed by filtration and the ethanol removed under reducedpressure. The residue was treated with sodium carbonate solution andthen extracted with chloroform. The combined chloroform extracts weredried (MgSO₄) and evaporated to give an oil. The product was separatedfrom starting material by purification using an alumina column elutedwith chloroform. The resulting oil was dissolved in diethyl ether andacidified with ethereal HCl to give the title compound as thehydrochloride, (0.47 g,) m.p 172°-4° C.

Analysis: Found C, 75.3; H, 7.8; N, 4.4. C₁₉ H₂₃ N.HCl requires C, 75.6;H, 8.0; N, 4.6%.

EXAMPLE 82-(6,7,8,9-Tetrahydro-5H-cyclohepta[b]pyrid-2-yl)-1-4-methylphenyl)ethanol

To a solution of 1.6M n-butyl lithium in n-hexane (7.2 ml) in toluene(25 ml), at -20° C. under nitrogen, was added a solution of2-methyl-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine (1.7 g 0.01 m) intoluene (5 ml). The solution was left to stir at -20° C. for 0.75 hours,then blown over into a solution of 4-methylbenzaldehyde (1.5 g). Thesolution was allowed to warm to room temperature and water added. Thetoluene phase was extracted with 2N hydrochloric acid and this wasbasified with solid potassium carbonate and then extracted withdichloromethane. The combined dichloromethane extracts were washed withwater, dried (MgSO₄) and evaporated to give an oil. This was purified bychromatography on basic alumina using diisopropyl ether as eluent togive the title compound as an oil. This was dissolved in ether andtreated with ethereal HCl to give a crystalline hydrochloride salt (1.2g) m.p. 184°-6° C.

Analysis: Found C, 71.7; H, 7.6; N, 4.2 C₁₉ H₂₃ NO, HCl requires C,71.8; 4, 7.6; N, 4.4%.

EXAMPLE 91-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methylamine

a) To a solution of 1.6M n-butyl lithium in n-hexane (16.5 ml) intoluene (20 ml) at -20° C. under nitrogen was added a solution of2-bromo-6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyridine (6.0 g,0.02 m) in toluene (30 ml). The reaction mixture was kept at -20° C. for0.25 hours and then blown over into a solution of 4-methyl benzonitrile(3.2 g) in toluene (30 ml) at -20° C. Then mixture was allowed to warmto room temperature. The solvent was removed under reduced pressure togive1-(6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(4-methylphenyl)methylimine.

b) Ethanol (150 ml) was added to the product of step (a) followed bysmall portions of sodium borohydride (1.2 g). After stirring at roomtemperature for 0.75 hours, 2N hydrochloric acid was added untilhydrogen evolution had ceased. The solvent was removed under reducedpressure and the residue treated with sodium bicarbonate solution andextracted with chloroform. The combined chloroform extracts were washedwith water, dried (MgSO₄) and evaporated. The residue was purified bychromatography on basic alumina, eluted with chloroform to give an oil.This was dissolved in diethyl ether and treated with ethereal HCl togive the title compound as the dihydrochloride, monohydrate salt, (1.93g)m.p. 178°-180° C.

Analysis: Found C, 61.7; H, 7.3; N, 7.8 C₁₉ H₂₄ N₂. 2HCl H₂ O requiresC, 61.45; H, 7.6; N, 7.5%.

EXAMPLE 101-(3--Chlorophenyl)-1-(6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)methanol

To a solution of 1.6M n-butyl lithium in n-hexane (16.5 ml) in toluene(20 ml) at -20° C. under nitrogen was added a solution of2-bromo-6,7,8,9-tetrahydro-3-methyl -5H-cyclohepta[b]pyridine (6.0 g,0.025 m) in toluene (30 ml). The reaction mixture was kept at -20° C.for 0.25 hours and then blown over into a cooled solution of3-chlorobenzaldehyde (3.7 g) in toluene (30 ml) at -20° C., and allowedto warm to room temperature. Water was added and the separated organicphase extracted with 2N hydrochloric acid. This was basified with solidpotassium carbonate and extracted with chloroform. The combinedchloroform extracts were washed with water, dried (MgSO₄) andevaporated. The solid was purified by passing through a short silicacolumn, eluted with chloroform, then re-crystallised from diethyl etherto give the title compound (4.31 g) m.p. 123°-5° C.

Analysis: Found C, 71.4; H, 6.8; N, 5.0 C₁₈ H₂₀ ClNO requires C, 71.6;H, 6.7;N, 4.6%.

EXAMPLE 111-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(3-methoxyphenyl)methanol

To a solution of 1.6M n-butyl lithium in n-hexane (16.5 m,) in toluene(20 ml) at -20°, under nitrogen, was added a solution of2-bromo-6,7,8,9-tetrahydro-3-methyl 5-H-cyclohepta[b]pyridine (6 g,0.025 m) in toluene (30 ml). The reaction mixture was kept at -20° C.for 0.25 hours and then blown over into a cooled solution (-20° C.) of3-methoxybenzaldehyde (3.7 g) in toluene (30 ml) and allowed to warm upto room temperature. Water was added and the organic phase separated andtreated with 2N hydrochloric acid. A precipitate formed and this wascollected by filtration and treated with sodium carbonate solution, thenchloroform. The organic phase was washed with water, dried (MgO₄) andevaporated. Trituration with diethyl ether gave1-(6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(3-methoxyphenyl)methanol(4.42 g, 59%) m.p. 104°-6° C.

Analysis: Found C, 76.9; H, 7.8; N,4.85 C₁₉ H₂₃ NO₂ requires C, 76.7; H,7.8; N, 4.7%).

EXAMPLE 121-(4-Trifluoromethylphenyl)-1-(6,7,8,9-tetrahydro-3--methyl-5H-cyclohepta[b]pyrid-2-yl)methanol

To a solution of 1.6M n-butyl lithium in n-hexane (16.5 ml) in toluene(20 ml) at -20° C., under nitrogen, was added a solution of2-bromo-6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyridine (6.0 g,0.025 m) in toluen (30 ml). The reaction mixture was kept at -20° C. for0.25 hours and then blown over into a solution ofa,a,a-tri-fluoro-p-tolualdehyde (4.7 g) in toluene (30 ml) at -20° C.The solution was allowed to warm up to room temperature and water added.The organic phase was separated with 2N hydrochloric acid. This wasbasified with solid potassium carbonate and extracted with chloroform.The combined chloroform extracts were dried (MgSO₄) and evaporated. Theresidue was recrystallised from n-hexane to give the title compound,(5.05 g) m.p. 131°-3° C.

Analysis: Found C, 68.0; H, 5.9; N, 4.5 C₁₉ H₂₀ F₃ NO requires C,68.05;H, 6.0; N, 4.2%.

EXAMPLE 131-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(pyrid-3-yl)methanol

To a solution of 1.6M n-butyl lithium in n-hexane (16.5 ml) in toluene(20 ml) at -20° C., under nitrogen, was added a solution of2-bromo-6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyridine (6 g, 0.025m) in toluene (30 ml) and kept at -20° C. for 0.25 hours. This was blownover into a solution of 3-pyridine carboxaldehyde (2.7 g) in toluene (30ml) kept at -20° C. The solution was allowed to warm up to roomtemperature and water added. The organic phase was separated, dried(MgSO₄) and evaporated. The solid was recrystallised from ether (twice)to give1-(6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(pyrid-3-yl)methanol(4.32 g, 64%) m.p. 124°-6° C.

Analysis Found C,75.8; H, 7.5; N, 10. 4. C₁₇ H₂₀ N₂ O requires C, 76.1;H, 7.5; N, 10.4%.

EXAMPLE 141-(6,7,8,9-Tetrahydro-3-methyl-5H-cyclohepta[b]pyrid-2-yl)-1-(thiophen-2-yl)methanol

To a solution of 1.6M n-butyl lithium in n-hexane (16.5 ml) in toluene(20 ml) at -70° C., under nitrogen, was added a solution of2-bromo-6,7,8,9-tetrahydro-3-methyl-5H-cyclohepta[b]pyridine (6 g 0.025m) and the mixture kept at -20° C. for 0.25 hours. This was blown overinto a solution of 2-thiophenecarboxaldehyde (3.0 g) in toluene (30 ml)kept at -20° C., then allowed to warm to room temperature and wateradded. The organic phase was extracted with 2N hydrochloric acid, thenbasified with solid potassium carbonate and extracted with chloroform.The combined chloroform extracts were dried (MgSO₄) and evaporated. Theresidue was recrystallised from n-hexane to give the title compound(4.42 g), m.p. 102°-4° C.

Analysis: Found C, 70.4; H, 7.15; N, 5 3 C₁₆ H₁₉ NOS requires C, 70.3;H, 7.0; N, 5.1%.

EXAMPLES 15-20

Using a procedure analogous to Example 6 the following compounds offormula I are prepared according to the reaction scheme

    ______________________________________                                         ##STR11##                                                                     ##STR12##                                                                    Example No                                                                             n       R.sup.8                                                                              R.sup.1 R.sup.2                                                                            mp                                       ______________________________________                                        15       3       Me     Me      H    123-4° C.                         16       4       Me     Me      H    88-90° C.                         17       6       Me     Me      H    118-120° C.                       18       5       Et     Me      H                                             19       5       H      H       Me                                            20       5       H      H       H                                             ______________________________________                                    

The following examples illustrate the new route to starting materials offormula (IV) used in some of the aforementioned Examples:

EXAMPLE 21 2--Bromo-3-methyl-6,7,8,9-tetrahydro-5H-cyclohepta[b]pyridine

a) Cycloheptanone was converted to an enamine by reaction withpyrrolidine in toluene solvent and in the presence of toluenesulphonicacid. The enamine was alkylated with methacrylonitrile in ethanolsolvent and hydrolysed using acetic acid according to the procedure ofStark et al, J. Amer. Chem, Soc., 85, 207 (1963) to give2-(2-cyanopropyl)cycloheptanone (bp 100° C./0.02 mmHg).

b) The product of step (a) (88 g, 0.5 m) in acetic acid (11) was treatedwith bromine (26 ml, 0.5 m) over 15 minutes, maintaining an internaltemperature of ca, 15° C. The mixture was allowed to warm to roomtemperature overnight. The solvent was evaporated off under reducedpressure and the residue partitioned between water and diisopropylether. The organic phase was dried (MgSO₄) and evaporated to give aresidue which on recrystallising from hexane gave the title compound aswhite needles, mp 68-70.

EXAMPLES 22-24

By a process analogous to Example 21 using the appropriate cycloalkanonethe following compounds of formula IV wherein p is O and Z is Br wereprepared:

22. 2-Bromo-3-methyl -5,6,7,8-tetrahydroquinoline, m.p. 50°-2° C.

23. 2-Bromo-3-methyl-5H-cyclopenta[b]pyridine.

24. 2-Bromo-3-methyl-5H-cycloocta[b]pyridine.

As illustrated in Example 21 compounds of formula VII may be preparedfrom cyclic ketone precursors via enamines by Michael alkylation tointroduce the --CHR² CHR¹ CN moiety.

We claim:
 1. A process for preparing a compound of formula IVa ##STR13##wherein R¹ and R² each independently represent hydrogen, lower alkyl,lower alkoxy, carboxyloweralkyl, carboxy, hydroxyloweralkyl, halogen,haloloweralkyl, lower alkoxycarbonyl, optionally substituted aryl oroptionally substituted aralkyl,n represents an integer from 3 to 6, R³which is optionally present represents single or multiple substitutionon one or more of the aliphatic carbons by one or more substituentsselected from lower alkyl, optionally substituted aryl and optionallysubstituted aralkyl, which comprises reacting a compound of formula VII##STR14## where n, R¹, R² and R³ are as defined above, in an inertsolvent with either HBr and bromine or with bromine.